As is known in the art, feed structures are used to couple a radar or communication system to an array of antenna elements. One component of a feed structure is a circulator. U.S. Pat. No. 5,374,241 entitled “Dual Junction Back-To-Back Microstrip Four-Port Circulators” describes a back-to-back four port microstrip circulator configured from two three-port single junction circulators whose substrates lay back-to-back and are interconnected with a coaxial feedthrough. The teachings of U.S. Pat. No. 5,374,241 describe the advantages of such a configuration.